/*******************************************************************************
 * Copyright (c) 2011 Google, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Google, Inc. - initial API and implementation
 *******************************************************************************/
package org.eclipse.wb.core.controls.jface.preference;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.preference.FieldEditor;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;

/**
 * A field editor for a combo box that allows the drop-down selection of one of a list of items.
 *
 * @since 3.3
 * @coverage core.control
 */
public class ComboFieldEditor extends FieldEditor {
  /**
   * The <code>Combo</code> widget.
   */
  private Combo fCombo;
  /**
   * The value (not the name) of the currently selected item in the Combo widget.
   */
  private String fValue;
  /**
   * The names (labels) and underlying values to populate the combo widget. These should be arranged
   * as: { {name1, value1}, {name2, value2}, ...}
   */
  private final String[][] fEntryNamesAndValues;

  /**
   * Create the combo box field editor.
   *
   * @param name
   *          the name of the preference this field editor works on
   * @param labelText
   *          the label text of the field editor
   * @param entryNamesAndValues
   *          the names (labels) and underlying values to populate the combo widget. These should be
   *          arranged as: { {name1, value1}, {name2, value2}, ...}
   * @param parent
   *          the parent composite
   */
  public ComboFieldEditor(String name,
      String labelText,
      String[][] entryNamesAndValues,
      Composite parent) {
    init(name, labelText);
    Assert.isTrue(checkArray(entryNamesAndValues));
    fEntryNamesAndValues = entryNamesAndValues;
    createControl(parent);
  }

  /**
   * Checks whether given <code>String[][]</code> is of "type" <code>String[][2]</code>.
   *
   * @return <code>true</code> if it is ok, and <code>false</code> otherwise
   */
  private boolean checkArray(String[][] table) {
    if (table == null) {
      return false;
    }
    for (int i = 0; i < table.length; i++) {
      String[] array = table[i];
      if (array == null || array.length != 2) {
        return false;
      }
    }
    return true;
  }

  /* (non-Javadoc)
   * @see org.eclipse.jface.preference.FieldEditor#adjustForNumColumns(int)
   */
  @Override
  protected void adjustForNumColumns(int numColumns) {
    if (numColumns > 1) {
      Control control = getLabelControl();
      int left = numColumns;
      if (control != null) {
        ((GridData) control.getLayoutData()).horizontalSpan = 1;
        left = left - 1;
      }
      ((GridData) fCombo.getLayoutData()).horizontalSpan = left;
    } else {
      Control control = getLabelControl();
      if (control != null) {
        ((GridData) control.getLayoutData()).horizontalSpan = 1;
      }
      ((GridData) fCombo.getLayoutData()).horizontalSpan = 1;
    }
  }

  /* (non-Javadoc)
   * @see org.eclipse.jface.preference.FieldEditor#doFillIntoGrid(org.eclipse.swt.widgets.Composite, int)
   */
  @Override
  protected void doFillIntoGrid(Composite parent, int numColumns) {
    int comboC = 1;
    if (numColumns > 1) {
      comboC = numColumns - 1;
    }
    Control control = getLabelControl(parent);
    GridData gd = new GridData();
    gd.horizontalSpan = 1;
    control.setLayoutData(gd);
    control = getComboBoxControl(parent);
    gd = new GridData();
    gd.horizontalSpan = comboC;
    gd.horizontalAlignment = GridData.FILL;
    control.setLayoutData(gd);
    control.setFont(parent.getFont());
  }

  /* (non-Javadoc)
   * @see org.eclipse.jface.preference.FieldEditor#doLoad()
   */
  @Override
  protected void doLoad() {
    updateComboForValue(getPreferenceStore().getString(getPreferenceName()));
  }

  /* (non-Javadoc)
   * @see org.eclipse.jface.preference.FieldEditor#doLoadDefault()
   */
  @Override
  protected void doLoadDefault() {
    updateComboForValue(getPreferenceStore().getDefaultString(getPreferenceName()));
  }

  /* (non-Javadoc)
   * @see org.eclipse.jface.preference.FieldEditor#doStore()
   */
  @Override
  protected void doStore() {
    if (fValue == null) {
      getPreferenceStore().setToDefault(getPreferenceName());
      return;
    }
    getPreferenceStore().setValue(getPreferenceName(), fValue);
  }

  /* (non-Javadoc)
   * @see org.eclipse.jface.preference.FieldEditor#getNumberOfControls()
   */
  @Override
  public int getNumberOfControls() {
    return 2;
  }

  /*
   * Lazily create and return the Combo control.
   */
  private Combo getComboBoxControl(Composite parent) {
    if (fCombo == null) {
      fCombo = new Combo(parent, SWT.READ_ONLY);
      fCombo.setFont(parent.getFont());
      for (int i = 0; i < fEntryNamesAndValues.length; i++) {
        fCombo.add(fEntryNamesAndValues[i][0], i);
      }
      fCombo.addSelectionListener(new SelectionAdapter() {
        @Override
        public void widgetSelected(SelectionEvent evt) {
          String oldValue = fValue;
          String name = fCombo.getText();
          fValue = getValueForName(name);
          setPresentsDefaultValue(false);
          fireValueChanged(VALUE, oldValue, fValue);
        }
      });
    }
    return fCombo;
  }

  /*
   * Given the name (label) of an entry, return the corresponding value.
   */
  private String getValueForName(String name) {
    for (int i = 0; i < fEntryNamesAndValues.length; i++) {
      String[] entry = fEntryNamesAndValues[i];
      if (name.equals(entry[0])) {
        return entry[1];
      }
    }
    return fEntryNamesAndValues[0][0];
  }

  /*
   * Set the name in the combo widget to match the specified value.
   */
  private void updateComboForValue(String value) {
    fValue = value;
    for (int i = 0; i < fEntryNamesAndValues.length; i++) {
      if (value.equals(fEntryNamesAndValues[i][1])) {
        fCombo.setText(fEntryNamesAndValues[i][0]);
        return;
      }
    }
    if (fEntryNamesAndValues.length > 0) {
      fValue = fEntryNamesAndValues[0][1];
      fCombo.setText(fEntryNamesAndValues[0][0]);
    }
  }
}
